fn:namespace-uri

fn:namespace-uri() as xs:anyURI

fn:namespace-uri($arg as node()?) as xs:anyURI

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context node (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If the node identified by $arg is neither an element nor an attribute node, or if it is an element or attribute node whose expanded-QName (as determined by the dm:node-name accessor in the node-name Accessor) is in no namespace, then the function returns the zero-length xs:anyURI value.

Otherwise, the result will be the namespace URI part of the expanded-QName of the node identified by $arg, as determined by the dm:node-name accessor defined in node-name Accessor), returned as an xs:anyURI value.

The following errors may be raised when $arg is omitted:

If the context item is absent, dynamic error [ERRXPDY0002]

If the context item is not a node, type error [ERRXPTY0004].